The present invention relates to a method of recovering palladium simply and effectively by electrolysis from an aqueous solution containing palladium and acidified with nitric acid, and also relates to an apparatus for carrying out the method.
The present invention is particularly useful in recovering palladium from radioactive liquid waste containing a plurality of elements of the platinum group, such as palladium, ruthenium and the like, which are nuclear fission products.
In most of the reported research for the separation and recovery of palladium from radioactive liquid waste or the like containing palladium, a chemical process of forming a precipitate or complex out of a solution is generally used.
In general industries, on the other hand, most processes for the separation and purification of palladium from palladium containing solutions employ solvent extraction.
The conventional process that depends on the formation of a precipitate or complex for the separation and recovery of palladium from radioactive liquid waste requires that a chemical substance containing an element to form the precipitate or complex be added from the outside into the liquid waste. This consequently brings about the increase in the amount of the waste to be treated. From the viewpoint of radioactive waste disposal, the increase in the amount of waste by the addition of the extra chemical substance from the outside is inadvisable. Moreover, the process involves complicated settings of operation conditions since it needs precise control of conditions, such as the additive concentrations and stoichiometric ratio, to suppress side reactions and optimize the chemical reactions.
Solvent extraction likewise necessitates a troublesome procedure of extracting palladium from a solution by the action of other chemical substance such as a solvent and further recovering palladium from the extract.